QOL make our gem requireable and autoload/eager load some constants

.gitattributes

@@ -1 +1,3 @@
 lib/protoboeuf/google/**/*.rb linguist-generated=true
+test/fixtures/autoloadergen/google/**/*.rb linguist-generated=true
+test/fixtures/autoloadergen/google/test_protos.correct.rb linguist-generated=false

.gitignore

@@ -5,5 +5,7 @@ Gemfile.lock
 # Code generated by protoboeuf
 test/fixtures/*_pb.rb
 test/fixtures/typed_test.generated.rb
+test/fixtures/autoloadergen/google/**/*.rb
+!test/fixtures/autoloadergen/google/test_protos.correct.rb
 bench/lib/
 bench/tmp/

Rakefile

@@ -7,9 +7,17 @@ require "rubocop/rake_task"
 RuboCop::RakeTask.new
 
 BASE_DIR = File.dirname(__FILE__)
-codegen_rb_files = ["lib/protoboeuf/codegen.rb"]
-proto_files = Rake::FileList[File.join(BASE_DIR, "test/fixtures/*.proto")]
-rb_files = proto_files.pathmap("#{BASE_DIR}/test/fixtures/%n_pb.rb")
+LIB_DIR = File.expand_path(BASE_DIR, "lib")
+
+codegen_rb_files = ["lib/protoboeuf/codegen.rb", "lib/protoboeuf/autoloadergen.rb"]
+
+# Fixture protos we want to compile with protoc
+protoc_test_fixtures = Rake::FileList[File.join(BASE_DIR, "test/fixtures/*.proto")]
+protoc_test_fixtures_rb_files = protoc_test_fixtures.pathmap("#{BASE_DIR}/test/fixtures/%n_pb.rb")
+
+# Fixture protos we want to compile with protoboeuf
+protoboeuf_test_fixtures = Rake::FileList[File.join(BASE_DIR, "test/fixtures/autoloadergen/**/*.proto")]
+protoboeuf_test_fixtures_rb_files = protoboeuf_test_fixtures.pathmap("%X.rb")
 
 BENCHMARK_UPSTREAM_PB = "bench/lib/upstream/benchmark_pb.rb"
 BENCHMARK_PROTOBOEUF_PB = "bench/lib/protoboeuf/benchmark_pb.rb"
@@ -19,12 +27,16 @@ well_known_types = Rake::FileList[
 ]
 
 WELL_KNOWN_PB = well_known_types.pathmap("%X.rb")
+# For a directory like lib/protoboeuf/google/protobuf, create an autoloader in lib/protoboeuf/google/protobuf.rb
+WELL_KNOWN_AUTOLOADERS = well_known_types.pathmap("%d.rb").uniq
 
 # Clobber/clean rules
-rb_files.each { |x| CLOBBER.append(x) }
+protoc_test_fixtures_rb_files.each { |x| CLOBBER.append(x) }
+protoboeuf_test_fixtures_rb_files.each { |x| CLOBBER.append(x) }
 CLOBBER.append(BENCHMARK_UPSTREAM_PB)
 CLOBBER.append(BENCHMARK_PROTOBOEUF_PB)
 CLOBBER.append(WELL_KNOWN_PB)
+CLOBBER.append(WELL_KNOWN_AUTOLOADERS)
 
 rule ".rb" => ["%X.proto"] + codegen_rb_files do |t|
   codegen_rb_files.each { |f| require_relative f }
@@ -34,9 +46,10 @@ rule ".rb" => ["%X.proto"] + codegen_rb_files do |t|
 
   unit = Tempfile.create(File.basename(t.source)) do |f|
     File.unlink(f.path)
+
     sh(*[
       "protoc",
-      well_known_types.map { |file| ["-I", file.pathmap("%d")] }.uniq,
+      (well_known_types + [t.source]).map { |file| ["-I", file.pathmap("%d")] }.uniq,
       File.basename(t.source),
       "-o",
       f.path,
@@ -61,7 +74,27 @@ rule ".rb" => ["%X.proto"] + codegen_rb_files do |t|
   File.binwrite(t.name, ProtoBoeuf::CodeGen.new(unit).to_ruby(dest, options))
 end
 
-task well_known_types: WELL_KNOWN_PB
+rule ".rb" => "%X" do |t|
+  # Given lib/protoboeuf/google/protobuf/foo.rb and lib/protoboeuf/google/protobuf/bar.rb, generate
+  # lib/protoboeuf/google/protobuf.rb that looks like:
+  #
+  # module ProtoBoeuf
+  #   module Google
+  #     module Protobuf
+  #       autoload :FooMessage1, "proto_boeuf/google/protobuf/foo"
+  #       autoload :FooMessage2, "proto_boeuf/google/protobuf/foo"
+  #       autoload :BarMessage1, "proto_boeuf/google/protobuf/bar"
+  #     end
+  #   end
+  # end
+
+  require_relative "lib/protoboeuf/autoloadergen"
+
+  puts "writing autoloader module #{t.name}"
+  File.binwrite(t.name, ProtoBoeuf::AutoloaderGen.new(t.name).to_ruby)
+end
+
+task well_known_types: WELL_KNOWN_PB + WELL_KNOWN_AUTOLOADERS
 
 # Makefile-like rule to generate "_pb.rb"
 rule "_pb.rb" => "test/fixtures/%{_pb,}n.proto" do |task|
@@ -104,7 +137,7 @@ Rake::TestTask.new do |t|
 end
 
 desc "Regenerate protobuf files"
-task gen_proto: rb_files
+task gen_proto: protoc_test_fixtures_rb_files + protoboeuf_test_fixtures_rb_files
 
 task test: [:gen_proto, :well_known_types]
 task default: :test

lib/protoboeuf/autoloadergen.rb

@@ -0,0 +1,112 @@
+# frozen_string_literal: true
+
+require "erb"
+require "syntax_tree"
+require "pathname"
+
+module ProtoBoeuf
+  class AutoloaderGen
+    # This class generates top-level autoloader modules for our well known types.  Given autogenerated .rb files like:
+    #   - lib/protoboeuf/google/protobuf/foo.rb
+    #   - lib/protoboeuf/google/protobuf/bar.rb
+    #
+    # generate lib/protoboeuf/google/protobuf.rb that looks like:
+    #
+    # module ProtoBoeuf
+    #   module Google
+    #     module Protobuf
+    #       autoload :FooMessage1, "protoboeuf/google/protobuf/foo"
+    #       autoload :FooMessage2, "protoboeuf/google/protobuf/foo"
+    #       autoload :BarMessage1, "protoboeuf/google/protobuf/bar"
+    #     end
+    #   end
+    # end
+
+    BASE_LIB_DIR = File.expand_path("..", __dir__)
+
+    attr_reader :module_filename,
+      :child_ruby_filenames,
+      :generated_autoloader_module_parts,
+      :parent_module_parts,
+      :require_paths_for_child_constants
+
+    def initialize(module_filename, parent_module = "ProtoBoeuf::Google")
+      @module_filename = module_filename
+      @parent_module_parts = parent_module.split("::")
+
+      # Given lib/protoboeuf/google.rb, glob lib/protoboeuf/google/**/*.rb
+      @child_ruby_filenames = Dir[module_filename.pathmap("%X/**/*.rb")].sort
+      autoloader_full_module_name = nil
+
+      # Build a map of what we want to autoload :ConstantName => protoboeuf/require/path
+      @require_paths_for_child_constants = child_ruby_filenames.each_with_object({}) do |filename, require_paths|
+        child_constants = constants_for_child_ruby_filename(filename)
+        # For the autoloader_full_module_name we can just pick the first child constant we come across and take the
+        # first three parts.  For example, ProtoBoeuf::Google::Api::FieldBehavior would be ProtoBoeuf::Google::Api.
+        if @autoloader_module_name.nil?
+          autoloader_full_module_name = child_constants.first.split("::")[0..2].join("::")
+        end
+
+        # Make our absolute filename relative to the base lib directory for our autoload calls.
+        require_path = Pathname.new(filename).relative_path_from(BASE_LIB_DIR).sub_ext("")
+        child_constants.each do |child_constant|
+          # child_constant is fully qualified, but we just want the last part
+          require_paths[child_constant.split("::").last] = require_path
+        end
+      end
+
+      @generated_autoloader_module_parts = autoloader_full_module_name.split("::")
+    end
+
+    def to_ruby
+      SyntaxTree.format(ERB.new(<<~RUBY, trim_mode: "-").result(binding))
+        # frozen_string_literal: true
+        # rubocop:disable all
+
+        # Autogenerated by `rake well_known_types`.  Do not edit!
+        <%- generated_autoloader_module_parts.each do |module_name| -%>
+          module <%= module_name %>
+        <%- end -%>
+
+        <%-
+          # Iterating over the sorted keys gives us lexographically sorted autoload statements
+        -%>
+        <%- require_paths_for_child_constants.keys.sort.each do |constant_name| -%>
+          <%- require_path = require_paths_for_child_constants[constant_name] -%>
+          autoload :<%= constant_name %>, "<%= require_path %>"
+        <%- end -%>
+
+        <%- generated_autoloader_module_parts.each do |module_name| -%>
+          end
+        <%- end -%>
+      RUBY
+    end
+
+    private
+
+    def constants_for_child_ruby_filename(filename)
+      @constants_for_child_ruby_filename ||= {}
+
+      return @constants_for_child_ruby_filename[filename] if @constants_for_child_ruby_filename.key?(filename)
+
+      loaded = Module.new do
+        module_eval File.binread(filename)
+      end
+
+      @constants_for_child_ruby_filename[filename] = loaded::ProtoBoeuf::Google.constants.flat_map do |const_name|
+        mod = loaded
+        parent_module_parts.each do |part|
+          mod = mod.const_get(part)
+        end
+        mod = mod.const_get(const_name)
+
+        next unless mod.is_a?(Module)
+
+        # The top-level module will be our anonymous Module we created above
+        parent_module_name = mod.name.split("::")[1..].join("::")
+
+        mod.constants.map { |const_name| "#{parent_module_name}::#{const_name}" }
+      end
+    end
+  end
+end

lib/protoboeuf/google.rb

@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
-# There isn't a clean 1:1 mapping between constants and *.rb files, so eager load instead of autoload.
-
-Dir[File.expand_path("google/**/*.rb", __dir__)].each { |file| require file }
+module ProtoBoeuf
+  module Google
+    autoload :Api, "protoboeuf/google/api"
+    autoload :Protobuf, "protoboeuf/google/protobuf"
+  end
+end

test/autoloadergen_test.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require "helper"
+require "protoboeuf/autoloadergen"
+
+class AutoloaderGenTest < ProtoBoeuf::Test
+  FIXTURE_PATH = File.expand_path("fixtures/autoloadergen/google", __dir__)
+
+  def test_generates_autoloader_module
+    # test/fixtures/autoloadergen/google/test_protos/*.proto needs an autoloader at
+    # test/fixtures/autoloadergen/google/test_protos.rb
+    autoloader_rb_path = File.expand_path("test_protos.rb", FIXTURE_PATH)
+
+    autoloader_ruby = ProtoBoeuf::AutoloaderGen.new(autoloader_rb_path).to_ruby
+
+    # If you ever want to regenerate the expected_autoloader_ruby, run:
+    # File.binwrite(File.expand_path("test_protos.correct.rb", FIXTURE_PATH), autoloader_ruby)
+    expected_autoloader_ruby = File.binread(File.expand_path("test_protos.correct.rb", FIXTURE_PATH))
+
+    assert_equal(expected_autoloader_ruby, autoloader_ruby)
+  end
+end

test/fixtures/autoloadergen/google/test_protos.correct.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+# rubocop:disable all
+
+# Autogenerated by `rake well_known_types`.  Do not edit!
+module ProtoBoeuf
+  module Google
+    module TestProtos
+      autoload :Bicycle,
+               "../test/fixtures/autoloadergen/google/test_protos/transportation"
+      autoload :Boat,
+               "../test/fixtures/autoloadergen/google/test_protos/transportation"
+      autoload :Color, "../test/fixtures/autoloadergen/google/test_protos/color"
+      autoload :Vehicle,
+               "../test/fixtures/autoloadergen/google/test_protos/transportation"
+    end
+  end
+end

test/fixtures/autoloadergen/google/test_protos/color.proto

@@ -0,0 +1,10 @@
+syntax = "proto3";
+
+package google.test_protos;
+
+enum Color {
+  UNKNOWN = 0;
+  RED = 1;
+  BLUE = 2;
+  GREEN = 3;
+}

test/fixtures/autoloadergen/google/test_protos/transportation.proto

@@ -0,0 +1,24 @@
+syntax = "proto3";
+
+package google.test_protos;
+
+import "color.proto";
+
+message Boat {
+  string make = 1;
+  int32 year = 2;
+  Color color = 3;
+}
+
+message Bicycle {
+  string make = 1;
+  int32 year = 2;
+  Color color = 3;
+}
+
+message Vehicle {
+  string make = 1;
+  string model = 2;
+  int32 year = 3;
+  Color color = 4;
+}

test/gem_test.rb

@@ -14,10 +14,12 @@ def test_can_be_required
 
         ::ProtoBoeuf
 
-        # The following should auto/eagerload
+        # The following should autoloaded
         ::ProtoBoeuf::CodeGen
         ::ProtoBoeuf::Google::Api::FieldBehavior
         ::ProtoBoeuf::Google::Protobuf::Any
+        ::ProtoBoeuf::Google::Protobuf::FileDescriptorProto
+        ::ProtoBoeuf::Google::Protobuf::FileDescriptorSet
 
         exit 0
       RUBY